Sampling of various aggregate materials is commonly required in the construction and mining industries to insure that the materials meet the required specifications for quality, composition and/or gradation. Samples of the aggregate product may be taken at various stages in the process from production or manufacture to delivery to the customer. Samples may be taken from stockpiles, silos or other storage facilities, or they may be taken from trucks, barges, railcars, conveyors or other transport vehicles.
It is common for producers of aggregate materials to sample their product at several stages, including the shipping stage. In addition, the purchaser will almost always sample at least a portion of the incoming shipments before unloading them to insure that they are acceptable. Aggregate materials that are hauled by truck are usually sampled by hand shoveling a sample portion from various locations in the aggregate load in the truck bed, in order to obtain a representative sample. Because the aggregate may segregate by size as it is being loaded and hauled, however, hand sampling in this way makes it difficult to obtain a representative sample. It is generally necessary to remove a portion of the surface material from several locations in the truck bed in order to obtain a sample portion from therebeneath. However, when the aggregate material is bituminous paving material such as asphalt concrete, its surface temperature may be as high as 250-300.degree. F., which makes hand sampling at least uncomfortable and potentially dangerous. Furthermore, a worker who is charged with the responsibility of obtaining a hand sample from an asphalt concrete truck will not likely be willing and may not be able to spend the time to take sample portions from various locations on the load in the truck bed to insure that he gets a representative sample. Nevertheless, the standard practice for sampling bituminous paving mixtures from truck transports is to take several portions of a sample from each truck using a flat-bottom scoop or a square-nose shovel.
ASTM Designation D 979-96 specifies that at least three approximately equal increments should be taken from each truck load of bituminous paving materials sampled. Various state highway departments impose additional requirements on the sampler of asphalt concrete, in an effort to insure that representative samples are obtained. For example, the Georgia Department of Transportation Sampling Procedure GSP-15 specifies that hand samples may be taken only after the "cone" of material in the bed of the truck is first shoveled off to a depth such that the resulting flat area is at least 60% as wide as the truck and at least six inches deep. Wyoming Department of Transportation Sampling Procedure 830.0 requires that for smaller trucks, a sample area must be prepared by removing the top 2-4 inches from each quarter of the load, while for larger trucks, at least two transverse trenches must be excavated across the load in the truck bed. The sample is then removed by pushing the shovel into each cleared area or trench at a 45.degree. angle. Illinois Department of Transportation Sampling Procedure 4.7.1 requires that an equal amount of material is to be taken from locations approximately one foot below the top of each pile in the truck bed, at quarter points around the pile's circumference. Mississippi Department of Transportation Field Testing Procedure TMD-11-77-00-000 requires that at least three samples be taken from specified locations in the truck after first removing the top 2-3 inches of material at each sample point. All of these procedures require that the sampler work for a significant period of time in the bed of the truck atop the load of hot asphalt concrete. Complying with such procedures is uncomfortable and may be dangerous, which makes proper sampling problematic.
It would be desirable therefore if a method and apparatus could be developed that would permit the taking of samples from a truck or other conveyance quickly and safely. It would also be desirable if such method and apparatus could be developed that would eliminate the need for the worker charged with obtaining the sample to climb into the truck bed and onto the load therein.